Low-drag rotor/wing flap

Abstract

Rotor/wing aircraft having a low-drag flap are disclosed. In one embodiment, a rotor/wing aircraft includes an elongated blade having a body portion and a flap portion. The body portion has first and second edges and includes a non-symmetric portion proximate the second edge. The flap portion is moveably coupled to the body portion proximate the second edge and is moveable between a rotary flight position and a forward flight position. In the rotary flight position, the flap portion is proximate at least part of the non-symmetric portion to form a second symmetric portion proximate the second edge. In the forward flight position, the flap portion extends away from the non-symmetric portion to form a tapered portion proximate the second edge.

1. A method of operating an aircraft, comprising:
 providing a plurality of elongated blades operatively coupled to a fuselage, a first one of the elongated blades including a body portion and a flap portion, the body portion having first and second edges and forming a non-symmetric portion proximate the second edge, the flap portion being moveably coupled to the body portion proximate the second edge; 
 positioning the flap portion in a rotary flight position wherein the flap portion is proximate at least part of the non-symmetric portion such that the non-symmetric portion and the flap portion combine to form a symmetric portion proximate the second edge; 
 generating lift in a vertical flight mode of operation including rotating the blade with the flap portion in the rotary flight position such that the second edge is a leading edge of the blade; 
 positioning the flap portion in a forward flight position wherein the flap portion extends away from the non-symmetric portion of the body portion to form a tapered portion proximate the second edge; and 
 generating lift in a forward flight mode of operation including fixing the blade in a stationary position with the flap portion in the forward flight position. 
 
   
   
     2. The method of  claim 1 , wherein providing an elongated blade including a body portion and a flap portion includes providing an elongated blade including an asymmetric flap portion. 
   
   
     3. The method of  claim 1 , wherein providing an elongated blade including a body portion and a flap portion includes providing an elongated blade having a body portion that includes upper and lower surfaces coupled together along the first and second edges, and a flap portion that includes first and second surfaces, and wherein positioning the flap portion in a rotary flight position includes positioning the first surface of the flap portion proximate at least part of the lower surface. 
   
   
     4. The method of  claim 3 , wherein positioning the flap portion in a rotary flight position includes positioning a concave portion of the first surface proximate a convex portion of the lower surface. 
   
   
     5. The method of  claim 3 , wherein positioning the flap portion in a rotary flight position includes positioning the flap portion at least partially within a recessed portion of the lower surface. 
   
   
     6. The method of  claim 1 , wherein generating lift in a forward flight mode of operation further includes propelling the elongated blade in a forward direction. 
   
   
     7. A method of operating an aircraft, comprising:
 providing a plurality of elongated blades moveably coupled to a fuselage, a first one of the elongated blades including a body portion having first and second edges and forming a non-symmetric portion proximate at least one of the first and second edges, and a flap portion moveably coupled to the body portion proximate the non-symmetric portion; 
 positioning the flap portion in a stowed position wherein the flap portion is proximate at least part of the non-symmetric portion such that the non-symmetric portion and the flap portion combine to form an at least approximate symmetric portion; 
 generating lift in a first operating mode including moving the blade such that the approximately symmetric portion is proximate a leading edge of the blade; 
 positioning the flap portion in a deployed position wherein the flap portion extends away from the non-symmetric portion; and 
 generating lift in a second operating mode including moving the blade such that the flap portion is proximate a trailing edge of the blade. 
 
   
   
     8. The method of  claim 7 , wherein generating lift in a first operating mode includes rotating the blade relative to the fuselage such that the approximately symmetric portion is proximate a leading edge of the blade. 
   
   
     9. The method of  claim 7 , wherein generating lift in a first operating mode includes fixing a position of the blade relative to the fuselage and propelling the elongated blade in a forward direction such that the approximately symmetric portion is a leading edge of the blade. 
   
   
     10. The method of  claim 7 , wherein the flap portion is a first flap portion, the method further comprising providing a second flap portion moveably coupled to the body portion proximate a second non-symmetric portion of the body portion, the second flap portion being positionable in a stowed position proximate at least part of the second non-symmetric portion such that the second non-symmetric portion and the second flap portion combine to form a second at least approximately symmetric portion, and in a deployed position wherein the second flap portion extends outward from the body portion. 
   
   
     11. The method of  claim 10 , wherein the first flap portion is moveably coupled to the first edge of the body portion and the second flap portion is moveably coupled to the second edge of the body portion. 
   
   
     12. The method of  claim 10 , wherein generating lift in the second operating mode includes positioning the second flap portion in the stowed position. 
   
   
     13. The method of  claim 10 , wherein generating lift in the first operating mode includes positioning the second flap portion in the deployed position.